[BUG] Salt master tries to access /etc/salt/grains when it shouldn't need to

Description When running the salt-master as non-root the service attempts to access /etc/salt/grains. As far as I'm aware it shouldn't need to access that file. The grains file should be reserved for the minion running on the host.

Setup RHEL9

[ ] on-prem machine
[x] VM (Redhat Virtualization)
[ ] VM running on a cloud service, please be explicit and add details
[ ] container (Kubernetes, Docker, containerd, etc. please specify)
[ ] or a combination, please be explicit
[ ] jails if it is FreeBSD
[ ] classic packaging
[x] onedir packaging
[ ] used bootstrap to install

Steps to Reproduce the behavior Install salt-master. Configure master to run as non-root.

cat << EOF > /etc/systemd/system/salt-master.service.d/override.conf
[Service]
User=salt
Group=salt
ExecStartPre=+chown salt:salt -R /etc/salt/pki/master /etc/salt/master /etc/salt/master.d /var/cache/salt/master /var/run/salt/master /var/log/salt
EOF
systemctl daemon-reload

Expected behavior To not try and access the grains file. Or at least don't error.

Screenshots

Traceback (most recent call last):
  File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/__init__.py", line 1188, in grains
    ret = funcs[key](**kwargs)
  File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 160, in __call__
    ret = self.loader.run(run_func, *args, **kwargs)
  File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 1269, in run
    return self._last_context.run(self._run_as, _func_or_method, *args, **kwargs)
  File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/loader/lazy.py", line 1284, in _run_as
    return _func_or_method(*args, **kwargs)
  File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/grains/extra.py", line 57, in config
    with salt.utils.files.fopen(gfn, "rb") as fp_:
  File "/opt/saltstack/salt/lib/python3.10/site-packages/salt/utils/files.py", line 388, in fopen
    f_handle = open(  # pylint: disable=resource-leakage,unspecified-encoding 
PermissionError: [Errno 13] Permission denied: '/etc/salt/grains'

Versions Report

salt --versions-report

```yaml Salt Version: Salt: 3007.1 Python Version: Python: 3.10.14 (main, Apr 3 2024, 21:30:09) [GCC 11.2.0] Dependency Versions: cffi: 1.16.0 cherrypy: unknown dateutil: 2.8.2 docker-py: Not Installed gitdb: Not Installed gitpython: Not Installed Jinja2: 3.1.4 libgit2: Not Installed looseversion: 1.3.0 M2Crypto: Not Installed Mako: Not Installed msgpack: 1.0.7 msgpack-pure: Not Installed mysql-python: Not Installed packaging: 23.1 pycparser: 2.21 pycrypto: Not Installed pycryptodome: 3.19.1 pygit2: Not Installed python-gnupg: 0.5.2 PyYAML: 6.0.1 PyZMQ: 25.1.2 relenv: 0.16.0 smmap: Not Installed timelib: 0.3.0 Tornado: 6.3.3 ZMQ: 4.3.4 Salt Package Information: Package Type: onedir System Versions: dist: rhel 9.4 Plow locale: utf-8 machine: x86_64 release: 5.14.0-427.20.1.el9_4.x86_64 system: Linux version: Red Hat Enterprise Linux 9.4 Plow ```

saltstack / salt

[BUG] Salt master tries to access /etc/salt/grains when it shouldn't need to #66746